Square-planar Tetranuclear Cluster-based Alkaline Earth Metal-organic Frameworks with Enhanced Proton Conductivity.

Alkaline earth (AE) metal complexes have garnered significant interest in various functional fields due to their nontoxicity, low density, and low cost. However, there is a lack of systematic investigation into the structural characteristics and physical properties of AE-metal-organic frameworks (MOFs). In this research, we synthesized isostructural MOFs consisting of AE4(µ4-Cl) clusters bridged by benzo-(1,2;3,4;5,6)-tris(thiophene-2'-carboxylic acid) (BTTC3-) ligands. The resulting structure forms a truncated octahedral cage denoted as [AE4(m4-Cl)]6(BTTC)8, which further linked to a porous three-dimensional framework. Among the investigated AE ions (Ca, Sr, and Ba), the Ca4-MOF demonstrated good chemical stability in water compared to Sr4-MOF and Ba4-MOF. The N2 adsorption and solid-state UV-vis-NIR absorption behaviors were evaluated for all AE4-MOFs, showing similar trends among the different metal ions. Additionally, the proton conduction study revealed that the Ca4-MOF exhibited ultra-high proton conductivity, reaching 3.52×10-2 S cm-1 at 343 K and 98 % RH. Notably, the introduction of LiCl via guest exchange resulted in an improved proton conduction of up to 6.36×10-2 S cm-1 under similar conditions in the modified LiCl@Ca4-MOF. The findings shed light on the regulation of physical properties and proton conductivity of AE-MOFs, providing valuable insights for their potential applications in various fields.

Artificial Skin with Patterned Stripes for Color Camouflage and Thermoregulation.

Chameleons are famous for their quick color changing abilities, and it is commonly assumed that they do this for camouflage. However, recent reports revealed that chameleons also change color for body temperature regulation. Inspired by the structure of the panther chameleon's skin, a stripe-patterned poly(N-isopropylacrylamide) (PNIPAM) and polyacrylamide (PAM) hydrogel film with a laminated structure is fabricated in this work; thus, both camouflage and thermoregulation can be achieved through controlling Vis and NIR light effectively. For the PNIPAM stripe, the upper layer is the native PNIPAM hydrogel and the lower layer is the carbon nanotube-composited PNIPAM hydrogel. Thus, the PNIPAM stripe is capable of reaching 28 °C at a low environmental temperature (12 °C) and a low radiation intensity (20 mW cm-2), while preventing the body temperature from rising by changing to white under a strong radiation intensity (100 mW cm-2). For the PAM stripe, the upper layer combines colloidal photonic crystals and displays a tunable structural color by stretching, and the lower layer is mixed with PNIPAM microgels for thermal regulation. Through the fabrication of multifunctional patterns, the film can achieve both dynamic structural color and thermoregulation by precisely controlling solar radiation absorption, scattering, and reflection. More importantly, in the stripe-patterned system, the shrinkage of the PNIPAM stripes can effectively trigger the elongation of the PAM stripe, which endows the structural color changing process to be self-powered completely. The performances show that the stripe-patterned film may have potential applications in intelligent coatings, especially in areas with large temperature differences during the day such as high plains.

Bio-Inspired Hydrogel-Elastomer Actuator with Bidirectional Bending and Dynamic Structural Color.

In nature, some creatures can change their body shapes and surface colors simultaneously to respond to the external environments, which greatly inspired researchers in the development of color-tunable soft actuators. In this work, we present a facile method to prepare a smart hydrogel actuator that can bend bidirectionally and change color simultaneously, just like an octopus. The actuator is fabricated by elastomer/hydrogel bilayer and the hydrogel layer was decorated with thermoresponsive microgels as the photonic crystal blocks. Compared with the previously reported poly(N-isopropylacrylamide) hydrogel-based bilayer hydrogel actuators, which are generally limited to one-directional deformation, the elastomer/hydrogel bilayer actuator prepared in our work exhibits unique bidirectional bending behavior in accordance with the change of structural color. The bending degrees can be changed from -360° to 270° in response to solution temperatures ranging from 20 °C to 60 °C. At the same time, the surface color changes from red to green, and then to blue, covering the full visible light spectrum. The bending direction and degree of the hydrogel actuator can easily be adjusted by tuning the layer thickness ratio of the elastomer/hydrogel or the composition of the hydrogel. The color-tunable hydrogel-elastomer actuator reported in this work can achieve both programmable deformations and color-changing highly resembling the natural actuating behaviors of creatures.

Cognitive diagnostic assessment of EFL learners' listening barriers through incorrect responses.

English as Foreign Language (EFL) learners' cognitive processes have been a research focus in listening assessment. Most studies use correct responses as data, but undervalue the rich information of the incorrect answers or options (in the case of multiple choice questions, MCQ). However, the MCQ distractors are often intentionally designed to reveal learners' problems or barriers. In order to diagnose the EFL learners' listening barriers through incorrect responses, Cognitive Diagnostic Models (CDMs) for bugs were adopted, hence the name Bug-CDMs. First, five EFL listening barrier attributes were identified and two Bug Q-matrices were developed to comparatively analyze the learner's responses with different Bug-CDMs. The results revealed that Bug-GDINA was the optimal model, and the most prevalent barriers were semantic understanding and vocabulary recognition. These barriers confirmed both compensatory and non-compensatory relationships in causing listening comprehension failures. The study proved the feasibility of Bug-GDINA in diagnosing listening barriers from the incorrect responses. Limitations and suggestions for further research were also proposed.

Cell-Free Expression of a Therapeutic Protein Serratiopeptidase.

Serratiopeptidase is a clinical therapeutic protein for the treatment of human diseases such as arthritis, bronchitis, and thrombosis. Yet production of this protein in a heterologous host (e.g., Escherichia coli) is difficult due to the issue of protein insolubility and the requirement of laborious refolding procedures. Cell-free protein synthesis (CFPS) systems, derived from crude cell extracts, are effective platforms for the expression of recombinant proteins in vitro. Here, we report a new method to produce serratiopeptidase by using an E. coli-based CFPS system. After rational selection of cell extracts and construction of expression vectors, soluble expression of serratiopeptidase was achieved and the enzyme activity could be readily tested in the cell-free reaction mixture. By further optimizing the key parameters, optimum conditions for the enzyme activity assay were obtained, including the pH value at 5, reaction temperature at 45 °C, substrate concentration at 10 mg/mL, and supplementing Ca2+ ions at 5 mM. Moreover, the CFPS mixture was freeze-dried and the activity of serratiopeptidase could be regenerated by hydration without losing activity. Overall, the CFPS system enabled soluble expression of serratiopeptidase with catalytic activity, providing a new and promising approach for this enzyme production. Our work extends the utility of the cell-free platform to produce therapeutic proteins with clinical applications.

Age-Related Differences of Mandarin Tone and Consonant Aspiration Perception in Babble Noise.

PURPOSE: This study investigated the categorical perception of Mandarin tones and consonant aspiration contrasts in babble noise among adults and adolescents aged 12-14 years, and explored the association between working memory and categorical perception. METHOD: Twenty-four adults and 20 adolescents with Mandarin as their native language were recruited. Their performances of phonemic identification and discrimination in babble noise and quiet conditions, digit span tasks, and nonword repetition were assessed. RESULTS: Results indicated that, firstly, in the noise condition, both adults and adolescents showed wider boundary widths and lower between-category accuracies when perceiving aspiration of consonants than in the quiet condition, and the categorical boundary of tone perception in adolescents showed a transitional tendency toward Tone 1. Secondly, discrimination of consonant aspiration in adolescents needed to be further developed. Lastly, the accuracy of nonword repetition in adolescents was lower than that in adults, and adults with better auditory verbal working memory had better performance on tone perception. CONCLUSIONS: Our results provided evidence that tone perception is acquired easier than consonant aspiration perception, and tone perception is more robust and less susceptible to noise interference. Categorical perception performance relates to the capacity and utilization of auditory verbal working memory in some ways.

Development of a single-molecule biosensor with an ultra-low background for the simultaneous detection of multiple retroviral DNAs.

Human T-cell lymphotropic virus type I and type II (HTLV-I and HTLV-II) are the two most prevalent subtypes of HTLVs, and they usually infect individuals asymptomatically and may induce various diseases. Herein, we develop a single-molecule biosensor with an ultra-low background for the simultaneous detection of multiple retroviral DNAs. This biosensor is constructed by immobilizing two types of signal probes (i.e., signal probes 1 and 2) onto the surface of magnetic beads (MBs) through specific biotin-streptavidin interactions. The presence of HTLV-I DNA and HTLV-II DNA will initiate the RNase H-assisted cyclic cleavage of signal probes, inducing the release of Cy3 and Cy5 fluorophores from the MBs. After magnetic separation, the Cy3 and Cy5 fluorophores can be directly quantified by single-molecule detection, with the Cy3 signal indicating HTLV-I DNA and the Cy5 signal indicating HTLV-II DNA. This biosensor enables the all-in-one and simultaneous detection of HTLV-I DNA and HTLV-II DNA under isothermal conditions, greatly simplifying the operation procedures and reducing the assay time. Due to the high amplification efficiency of RNase H-assisted target recycling, the ultra-low background resulting from magnetic separation, and the intrinsic high signal-to-noise ratio of single-molecule detection, this biosensor exhibits high sensitivity with a detection limit of 66.1 aM for HTLV-I DNA and 82.8 aM for HTLV-II DNA. Moreover, it can be applied for the discrimination of HTLV-positive cells from HTLV-negative cells, and even simultaneously quantify endogenous HTLV-I DNA and HTLV-II DNA at the single-cell level. Furthermore, this biosensor can be extended to detect other nucleotide molecules by rationally designing signal probes, providing a universal and powerful tool for clinical diagnosis and biomedical research.

Toward a Better Understanding of Language Learning Motivation in a Study Abroad Context: An Investigation Among Chinese English as a Foreign Language Learners.

Motivation has been recognized as a vital component in successfully learning a second or foreign language. However, research on language learners' motivation in a study abroad context requires more attention in an era in which international mobility is becoming a new normal. This study investigated 217 Chinese overseas university students' L2 motivation during their one-year postgraduate study in the United Kingdom. by examining a range of motivational variables in relation to their motivated English language learning behaviors. Integrating results from both questionnaires and interviews from nine participating students, the study revealed that international posture showed the strongest positive power, followed by the ideal L2 self, in explaining the learners' willingness to communicate, frequency of communication, and intended learning effort. Additionally, instrumentality and parental encouragement exerted prominent promotional influence in shaping their intended learning effort. However, the ought-to L2 self-displayed a significant negative impact on their L2 learning in this study abroad context, and the role of attitudes toward L2 speakers/community and culture was not evident in this case. The findings shed light on a more comprehensive understanding of L2 motivation in a study abroad context, and offer insightful implications for English as a Foreign Language education in cultivating language learners' motivation to prepare for study abroad.

Effects of Cognitive Load on the Categorical Perception of Mandarin Tones.

Purpose This study investigated the effect of cognitive load (CL) on the categorical perception (CP) of Mandarin lexical tones to discuss the application of the generalized pulse-skipping hypothesis. This hypothesis assumes that listeners might miss/skip temporal pulses and lose essential speech information due to CL, which consequently affects both the temporal and spectral dimensions of speech perception. Should CL decrease listeners' pitch sensitivity and impair the distinction of tone categories, this study would support the generalized pulse-skipping hypothesis. Method Twenty-four native Mandarin-speaking listeners were recruited to complete a dual-task experiment where they were required to identify or discriminate tone stimuli while concurrently memorizing six Chinese characters or graphic symbols. A no-load condition without a memory recall task was also included as a baseline condition. The position of categorical boundary, identification slope, between- and within-category discrimination, and discrimination peakedness were compared across the three conditions to measure the impact of CL on tone perception. The recall accuracy of Chinese characters and graphic symbols was used to assess the difficulty of memory recall. Results Compared with the no-load condition, both load conditions showed a boundary shift to Tone 3, shallower identification slope, poorer between-category discrimination, and lower discrimination peakedness. Within-category discrimination was negatively affected by CL in the graphic symbol condition only, not in the Chinese character condition. Conclusions CL degraded listeners' sensitivity to subtle fundamental frequency changes and impaired CP of Mandarin lexical tones. This provides support for the generalized pulse-skipping hypothesis. Besides, the involvement of lexical information modulated the effect of CL.

A trifunctional split dumbbell probe coupled with ligation-triggered isothermal rolling circle amplification for label-free and sensitive detection of nicotinamide adenine dinucleotide.

The nicotinamide adenine dinucleotide (NAD+) is an important small biomolecule that participates in a variety of physiological functions, and it has been regarded as a potential biomarker for disease diagnosis and a promising target for disease treatment. The conventional methods for NAD+ assay often suffer from complicated procedures, expensive labeling, poor selectivity, and unsatisfactory sensitivity. Herein, we develop a label-free and sensitive method for NAD+ assay based on the integration of a trifunctional split dumbbell probe with ligation-triggered isothermal rolling circle amplification (RCA). We design a trifunctional split dumbbell probe that can act as a probe for NAD+ recognition, a template for RCA reaction, and a substrate for SYBR Green I binding. In the presence of target NAD+, it can serve as a cofactor to active E. coli DNA ligase which subsequently catalyzes the ligation of split dumbbell probe to form a circular template for RCA reaction, generating numerous dumbbell probe amplicons which can be easily and label-free monitored by using SYBR Green I as the fluorescent indicator. Due to the high fidelity of NAD+-dependent ligation and high amplification efficiency of RCA amplification, this method exhibits high sensitivity with a detection limit of 85.6 fM and good selectivity with the capability of discriminating target NAD+ from its analogs. Moreover, this method can be applied for accurate and sensitive detection of NAD+ in complex biological samples and cancer cells, holding great potential in NAD+-related biological researches and clinical diagnosis.

Peptide-templated gold nanoparticle nanosensor for simultaneous detection of multiple posttranslational modification enzymes.

We developed a peptide-templated gold nanoparticle (AuNP) nanosensor for simultaneous detection of multiple posttranslational modification (PTM) enzymes with a detection limit of 28 pM for histone deacetylase (HDAC) and 0.8 pM for protein tyrosine phosphatase 1B (PTP1B), and it can be further applied for the screening of PTM enzyme inhibitors and the measurement of PTM enzymes in cancer cells.

An EM-Based Method for Q-Matrix Validation.

With the purpose to assist the subject matter experts in specifying their Q-matrices, the authors used expectation-maximization (EM)-based algorithm to investigate three alternative Q-matrix validation methods, namely, the maximum likelihood estimation (MLE), the marginal maximum likelihood estimation (MMLE), and the intersection and difference (ID) method. Their efficiency was compared, respectively, with that of the sequential EM-based δ method and its extension (ς2), the γ method, and the nonparametric method in terms of correct recovery rate, true negative rate, and true positive rate under the deterministic-inputs, noisy "and" gate (DINA) model and the reduced reparameterized unified model (rRUM). Simulation results showed that for the rRUM, the MLE performed better for low-quality tests, whereas the MMLE worked better for high-quality tests. For the DINA model, the ID method tended to produce better quality Q-matrix estimates than other methods for large sample sizes (i.e., 500 or 1,000). In addition, the Q-matrix was more precisely estimated under the discrete uniform distribution than under the multivariate normal threshold model for all the above methods. On average, the ς2 and ID method with higher true negative rates are better for correcting misspecified Q-entries, whereas the MLE with higher true positive rates is better for retaining the correct Q-entries. Experiment results on real data set confirmed the effectiveness of the MLE.